Zookeeper分布式锁生成订单号案例

男娘i 2024-04-18 14:47 68阅读 0赞

### 一、引入pom ###

<dependencies>
            <dependency>
                <groupId>org.apache.zookeeper</groupId>
                <artifactId>zookeeper</artifactId>
                <version>3.4.6</version>
            </dependency>
            <dependency>
                <groupId>com.101tec</groupId>
                <artifactId>zkclient</artifactId>
                <version>0.10</version>
            </dependency>
        </dependencies>

### 二、编写订单号生成器 （未加任何锁时） ###

package com.zhq.lock;
    
    import java.text.SimpleDateFormat;
    import java.util.Date;
    
    /**
     * @program: zookeeper
     * @description: 订单号生成器
     * @author: HQ Zheng
     * @create: 2019-09-08 13:18
     */
    public class OrderNumGenerator {
        private static int count =0;
    
        public String orderNumber(){
            SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd-HH-mm-ss");
            return simpleDateFormat.format(new Date())+"-"+ ++count;
        }
    }

### 三、 模拟多线程生成订单号 ###

package com.zhq.lock;
    
    /**
     * @program: zookeeper
     * @description: 订单服务
     * @author: HQ Zheng
     * @create: 2019-09-08 13:23
     */
    public class OrderService implements Runnable {
    
        private OrderNumGenerator orderNumGenerator = new OrderNumGenerator();
    
        public void run() {
            getOrderNumber();
        }
    
        public void getOrderNumber() {
            String number = orderNumGenerator.orderNumber();
            System.out.println(Thread.currentThread().getName()+",生成订单号：" + number);
        }
    
        /**
         * 模拟多线程生成订单号
         * @param args
         */
        public static void main(String[] args) {
            for (int i = 0; i < 100; i++) {
                new Thread(new OrderService()).start();
            }
    
        }
    }

运行结果：只要count没到100，就会有订单号重复

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3htMzkzMzkyNjI1_size_16_color_FFFFFF_t_70][]

### 四、如果是单体项目只需要加synchronized就能解决问题（单体项目） ###

private  static  Object lock=new Object();//锁
     
    public void  getOrderNumber() {
            synchronized (lock){
                String number = orderNumGenerator.orderNumber();
                System.out.println(Thread.currentThread().getName()+",生成订单号：" + number);
            }
        }

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3htMzkzMzkyNjI1_size_16_color_FFFFFF_t_70 1][]

### 五、如果是分布式集群项目 （分布式集群项目） ###

重构代码：

定义锁接口

package com.zhq.lock;
    
    public interface Lock {
    
        //获取锁
        public void getLock();
    
        //释放锁
        public void unLock();
    }

定义锁抽象类实现接口

package com.zhq.lock;
    
    import org.I0Itec.zkclient.ZkClient;
    
    /**
     * @program: zookeeper
     * @description: zookeeper锁抽象类
     * @author: HQ Zheng
     * @create: 2019-09-08 14:03
     */
    public abstract class ZookeeperAbstractLock implements Lock {
        private static final  String CONNECT_ADDRESS="192.168.43.104:2181";
        protected ZkClient zkClient=new ZkClient(CONNECT_ADDRESS);
        protected  static final  String PATH="/lock";
    
        //获取锁
        public void getLock(){
            if(tryLock()){
                System.out.println("获取到锁的资源");
            }else{
                //等待
                waitLock();
                //重新获取锁
                getLock();
            }
        }
    
        //锁等待
        protected abstract void waitLock();
    
        //判断释放获取资源
        protected abstract boolean tryLock();
    
        //释放锁
        public void unLock(){
            if(zkClient!=null){
                zkClient.close();
            }
            System.out.println("释放锁资源");
        }
    }

定义具体的锁资源节点内容类实现锁抽象类

package com.zhq.lock;
    
    import org.I0Itec.zkclient.IZkDataListener;
    
    import java.util.concurrent.CountDownLatch;
    
    /**
     * @program: zookeeper
     * @description: 实现锁
     * @author: HQ Zheng
     * @create: 2019-09-08 14:15
     */
    public class ZookeeperDistrbuteLock extends ZookeeperAbstractLock {
    
        private CountDownLatch countDownLatch= null;
    
        protected void waitLock() {
            //监听节点删除事件
            IZkDataListener iZkDataListener = new IZkDataListener() {
                //
                public void handleDataChange(String s, Object o) throws Exception {
    
                }
    
                //节点删除时
                public void handleDataDeleted(String s) throws Exception {
                    if (countDownLatch != null) {
                        //唤醒被等待的线程
                        countDownLatch.countDown();
                    }
                }
            };
            //注册到zkClient进行监听
            zkClient.subscribeDataChanges(PATH,iZkDataListener);
            if (zkClient.exists(PATH)) {
                countDownLatch=new CountDownLatch(1);
                try {
                    countDownLatch.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            //删除监听
            zkClient.unsubscribeDataChanges(PATH,iZkDataListener);
        }
    
        protected boolean tryLock() {
            try {
                zkClient.createEphemeral(PATH);
                return true;
            } catch (RuntimeException e) {
                return false;
            }
        }
    }

模拟分布式集群环境获取订单号

package com.zhq.lock;
    
    /**
     * @program: zookeeper
     * @description: 订单服务
     * @author: HQ Zheng
     * @create: 2019-09-08 13:23
     */
    public class OrderService implements Runnable {
    
        private OrderNumGenerator orderNumGenerator = new OrderNumGenerator();
    
        private Lock lock=new ZookeeperDistrbuteLock();//锁
    
        public void run() {
            getOrderNumber();
        }
    
        public void getOrderNumber() {
            //获取锁资源
            lock.getLock();
            String number = orderNumGenerator.orderNumber();
            System.out.println(Thread.currentThread().getName() + ",生成订单号：" + number);
            //释放锁资源
            lock.unLock();
        }
    
        /**
         * 模拟多线程生成订单号
         *
         * @param args
         */
        public static void main(String[] args) {
            for (int i = 0; i < 100; i++) {
                new Thread(new OrderService()).start();
            }
    
        }
    }

运行结果：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3htMzkzMzkyNjI1_size_16_color_FFFFFF_t_70 2][]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3htMzkzMzkyNjI1_size_16_color_FFFFFF_t_70]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/18/2ef4936e670a4eeca49a8056c41a9d6f.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3htMzkzMzkyNjI1_size_16_color_FFFFFF_t_70 1]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/18/65b9dbc43a394aa8a5d57668fca49674.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3htMzkzMzkyNjI1_size_16_color_FFFFFF_t_70 2]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/18/5bb23b57f7ae4406b91cc01a08b37045.png